A5088218011- Semiconductor Quantum Structures and Devices
- Chalcogenide Semiconductor Thin Films
- Semiconductor Lasers and Optical Devices
- Phase-change materials and chalcogenides
- Quantum Dots Synthesis And Properties
- Quantum and electron transport phenomena
- Quantum Information and Cryptography
- Mechanical and Optical Resonators
- 2D Materials and Applications
- Quantum optics and atomic interactions
- GaN-based semiconductor devices and materials
- Nonlinear Optical Materials Studies
- Advanced Semiconductor Detectors and Materials
- Advanced Thermoelectric Materials and Devices
- Neural Networks and Reservoir Computing
- Cold Atom Physics and Bose-Einstein Condensates
- Nanowire Synthesis and Applications
- Acoustic Wave Resonator Technologies
- Molecular Junctions and Nanostructures
- Advanced Fiber Laser Technologies
- Graphene research and applications
- Perovskite Materials and Applications
- ZnO doping and properties
- Quantum-Dot Cellular Automata
- Thermal Radiation and Cooling Technologies
Paul Drude Institute for Solid State Electronics
2016-2025
Schott (Germany)
2021-2025
Technical University of Munich
2021-2025
Forschungsverbund Berlin
2020-2025
Munich Center for Quantum Science and Technology
2023-2024
CeNTech
2023
Leibniz Institute for Solid State and Materials Research
2011-2019
St. Eugenio Hospital
2012
Atkins (United Kingdom)
2012
University of Rome Tor Vergata
2011
The lack of structural symmetry which usually characterizes semiconductor quantum dots lifts the energetic degeneracy bright excitonic states and hampers severely their use as high-fidelity sources entangled photons. We demonstrate experimentally theoretically that it is always possible to restore by simultaneous application large strain electric fields. This achieved using one external perturbation align polarization exciton emission along axis second perturbation, then erases completely...
Abstract The prospect of using the quantum nature light for secure communication keeps spurring search and investigation suitable sources entangled photons. A single semiconductor dot is one most attractive, as it can generate indistinguishable photons deterministically compatible with current photonic-integration technologies. However, lack control over energy hampering exploitation dissimilar dots in protocols requiring teleportation entanglement remote locations. Here we introduce...
We integrate resonant-cavity light-emitting diodes containing quantum dots onto substrates with giant piezoelectric response. Via strain, the energy of photons emitted by diode can be precisely controlled during electrical injection over a spectral range larger than 20 meV. Simultaneously, exciton fine-structure-splitting and biexciton binding tuned to values required for entangled photon generation. Light-emitting semiconductor (QLEDs) are among most promising sources non-classical light,1...
Triggered sources of entangled photons play crucial roles in almost any existing protocol quantum information science. The possibility to generate these non-classical states light with high speed and using electrical pulses could revolutionize the field. Entangled-light-emitting-diodes (ELEDs) based on semiconductor dots (QDs) are at present only devices that can address this task 5. However, ELEDs plagued by a source randomness hampers their practical exploitation foreseen applications:...
Abstract Phase Change Materials (PCMs) are unique compounds employed in non-volatile random access memory thanks to the rapid and reversible transformation between amorphous crystalline state that display large differences electrical optical properties. In addition amorphous-to-crystalline transition, experimental results on polycrystalline GeSbTe alloys (GST) films evidenced a Metal-Insulator Transition (MIT) attributed disorder phase. Here we report fundamental advance fabrication of GST...
Entanglement resources are key ingredients of future quantum technologies. If they could be efficiently integrated into a semiconductor platform new generation devices envisioned, whose quantum-mechanical functionalities controlled via the mature technology. Epitaxial dots (QDs) embedded in diodes would embody such ideal devices, but QD structural asymmetries lower dramatically degree entanglement sources and hamper severely their real exploitation foreseen applications. In this work, we...
Very low density growth of GaAs quantum dots in self-assembled nanoholes created by gallium droplet etching is demonstrated. The emission energy the can be accurately controlled deposition amount, from 1.8 to 1.6 eV, independently dot which reproducibly over range 0.2−2×10−8 cm−2 rate. ensemble full-width-half-maximum <10 meV and single-dot linewidths 40 μeV (limited our spectral resolution) have been measured. Additionally, shallow mounds on sample surface allow buried GaAs/AlGaAs...
Abstract A combination of far-infrared and Raman spectroscopy is employed to investigate vibrational modes the carrier behavior in amorphous crystalline ordered GeTe-Sb 2 Te 3 alloys (GST) epitaxially grown on Si(111). The infrared active GST mode not observed spectra vice versa, indication fact that inversion symmetry preserved metastable cubic phase accordance with F"Equation missing"<!-- image only, no MathML or LaTex -->m3 space group. For trigonal phase, instead, a partial break due...
Reversible biaxial strains are used for tuning the emission wavelengths of high quality GaAs/AlGaAs quantum dots (QDs) in spectral range 87Rb D2 lines. The strain is transferred by integrating free standing (Al)GaAs nanomembranes, containing QDs, onto piezoelectric actuators. Narrow excitonic lines as sharp 25 μeV shown, and a larger than 5 nm demonstrated. This corresponds to an induced anisotropic order 0.15%, evaluated from shift GaAs nanomembranes. presented on-chip technology...
Abstract Van der Waals (vdW) epitaxial growth of large-area and stable two-dimensional (2D) materials high structural quality on crystalline substrates is crucial for the development novel device technologies. 2D gallium monochalcogenides with low in-plane symmetry stand out among layered semiconductor family next-generation optoelectronic energy conversion applications. Here, we demonstrate formation large-area, single crystal optically active monoclinic telluride (m-GaTe) silicon substrate...
Abstract This paper reviews the recent advances obtained by integrating semiconductor epitaxial films with embedded self‐assembled quantum dots (QDs) on top of single‐crystal piezoelectric substrates made lead magnesium niobate–lead titanate (PMN‐PT). combination allows us to study in detail effects produced variable strains (up about ± 0.2%) excitonic emission single QDs and add a powerful “tuning knob” QDs. Biaxial stress can be used reversibly shift wavelength spectral range wider than 10...
We demonstrate the first wavelength-tunable electrically pumped source of nonclassical light that can emit photons with wavelength in resonance D2 transitions 87Rb atoms. The device is fabricated by integrating a novel GaAs single-quantum-dot light-emitting diode (LED) onto piezoelectric actuator. By feeding emitted into 75 mm long cell containing warm vapor, we observe slow-light temporal delay up to 3.4 ns. In view possibility using atomic vapors as quantum memories, this work makes an...
Enrichment of GeSbTe alloys with germanium has been proposed as a valid approach to increase the crystallization temperature and therefore address high-temperature applications non-volatile phase change memories, such embedded or automotive applications. However, tendency Ge-rich decompose segregation pure Ge still calls for investigations on basic mechanisms leading element diffusion compositional variations. With purpose identifying some possible routes limit segregation, in this study, we...
Abstract A scalable epitaxy of 2D layered materials and heterostructures constitutes a crucial step in developing novel optoelectronic applications based on high‐crystalline quality materials. Here, the formation continuous, strain‐free, hexagonal gallium telluride (h‐GaTe) directly epitaxial graphene using molecular beam is demonstrated. Morphological structural characterizations evidence coherent layer at heterostructure interface having an in‐plane lattice constant 4.05 ± 0.01 . The...
We investigate the effect of large in-plane strain and vertical electric fields on binding energies excitonic complexes confined in single InGaAs/GaAs quantum dots (QDs) we find that two independently tunable perturbations modify interaction among electrons holes a different manner. By taking advantage this difference, frequency-lock QD fundamental excitation (the neutral exciton) at predefined value, while biexciton transition is actively tuned from to an antibinding configuration. Our...
Abstract In recent years strain engineering is proposed in chalcogenide superlattices (SLs) to shape particular the switching functionality for phase change memory applications. This possible Sb 2 Te 3 /GeTe heterostructures leveraging on peculiar behavior of , between covalently bonded and weakly materials. present study, structural thermoelectric (TE) properties epitaxial 2+ x films are shown, as they represent an intriguing option expand horizon such SLs. Samples with composition 4...
Superlattices made of Sb2Te3/GeTe phase change materials have demonstrated outstanding performance with respect to GeSbTe alloys in memory applications. Recently, epitaxial superlattices were found feature GexSb2Te3+x blocks as a result intermixing between constituting layers. Here we present the epitaxy and characterization Sb2Te3/GexSb2Te3+x van der Waals superlattices, where was intentionally fabricated. X-ray diffraction, Raman spectroscopy, scanning transmission electron microscopy,...
The present work displays a route to design strain gradients at the interface between substrate and van der Waals bonded materials. latter are expected grow decoupled from substrates fully relaxed thus, by definition, incompatible with conventional engineering. By usage of passivated vicinal surfaces we able insert step edges layered chalcogenides, as demonstrated tilt epilayer in growth direction respect orientation. interplay classical epitaxy can be modulated an accurate choice miscut....
Abstract Scalable fabrication of magnetic 2D materials and heterostructures constitutes a crucial step for scaling down current spintronic devices the development novel applications. Here, we report on van der Waals (vdW) epitaxy layered metal Fe 3 GeTe 2 (FGT)—a crystal with highly tunable properties high prospect room temperature ferromagnetism (FM)—directly graphene by employing molecular beam epitaxy. Morphological structural characterization confirmed realization large-area, continuous...
This work presents an experimental method to tune the degree of heavy-hole (HH) and light-hole (LH) mixing ground state quantum dots (QDs). A ferroelectric crystal is used apply reversible anisotropic biaxial stress thin nanomembranes, containing GaAs/AlGaAs QDs. The stress-induced modification QD anisotropy leads a change relative intensity two emission lines produced by recombination neutral bright excitonic states. Such ascribed variation HH-LH mixing. At same time modified produces fine...
We demonstrate an all-electrically operated wavelength-tunable on demand single-photon source for the first time. The device consists of a light-emitting diode in form semiconductor nanomembrane containing self-assembled quantum dots integrated onto piezoelectric crystal. Triggered single photons are generated via injection ultrashort electrical pulses into diode, while their energy can be precisely tuned over broad range by varying voltage applied to High speed operation this...